Dec 31 (Reuters) - Comedic actress Betty White, who capped a career of more than 80 years by becoming America"s geriatric sweetheart after Emmy-winning roles on television sitcoms "The Golden Girls" and "The Mary Tyler Moore Show," died on Friday, less than three weeks shy of her 100th birthday. The agent, Jeff Witjas, told People magazine: "Even though Betty was about to be 100, I thought she would live forever." No cause was cited. In a youth-driven entertainment industry where an actress over 40 faces career twilight, White was an anomaly who was a star in her 60s and a pop culture phenomenon in her 80s and 90s. Playing on her eminent likability, White was still starring in a TV sitcom, "Hot in Cleveland," at age 92 until it was canceled in late 2014. White said her longevity was a result of good health, good fortune and loving her work. "It"s incredible that I"m still in this business and that you are still putting up with me," White said in an appearance at the 2018 Emmy Awards ceremony, where she was honored for her long career. "It"s incredible that you can stay in a career this long and still have people put up with you. I wish they did that at home." White was not afraid to mock herself and throw out a joke about her sex life or a snarky crack that one would not expect from a sweet-smiling, white-haired elderly woman. She was frequently asked if, after such a long career, there was anything she still wanted to do and the standard response was "Robert Redford." "She was great at defying expectation. She managed to grow very old and somehow, not old enough. We’ll miss you, Betty," former costar and friend Ryan Reynolds wrote in a Twitter post. "Old age hasn’t diminished her," the New York Times wrote in 2013. "It has given her a second wind." Minutes after news emerged of her death, U.S. President Joe Biden told reporters: "That"s a shame. She was a lovely lady." His wife Jill Biden said: "Who didn"t love Betty White? We"re so sad about her death." Betty Marion White was born on Jan. 17, 1922, in Oak Park, Illinois, and her family moved to Los Angeles during the Great Depression, where she attended Beverly Hills High School. A DEBUT IN THE 1930s Mourners gather around the Hollywood Walk of Fame star of actor Betty White, who died at the age of 99, in Los Angeles, California, U.S., December 31, 2021. REUTERS/David Swanson Cast member Betty White attends the premiere of the 3-D animated film "Dr. Seuss" The Lorax" in Los Angeles February 19, 2012. REUTERS/Phil McCarten/File Photo Actress Betty White accepts the favorite TV Icon award during the 2015 People"s Choice Awards in Los Angeles, California January 7, 2015. REUTERS/Mario Anzuoni/File Photo 1/8 Cast member Betty White attends the premiere of the 3-D animated film "Dr. Seuss" The Lorax" in Los Angeles February 19, 2012. REUTERS/Phil McCarten/File Photo White started her entertainment career in radio in the late 1930s and by 1939 had made her TV debut singing on an experimental channel in Los Angeles. After serving in the American Women"s Voluntary Service, which helped the U.S. effort during World War Two, she was a regular on "Hollywood on Television," a daily five-hour live variety show, in 1949. A few years later she became a pioneering woman in television by co-founding a production company and serving as a co-creator, producer and star of the 1950s sitcom "Life with Elizabeth." Through the 1960s and early "70s White was seen regularly on television, hosting coverage of the annual Tournament of Rose Parade and appearing on game shows such as "Match Game" and "Password." She married "Password" host Allen Ludden, her third and final husband, in 1963. White reached a new level of success on "The Mary Tyler Moore Show," playing the host of a home-making television show, the snide, lusty Sue Ann Nivens, whose credo was "a woman who does a good job in the kitchen is sure to reap her rewards in other parts of the house." White won best-supporting actress Emmys for the role in 1975 and 1976. She won another Emmy in 1986 for "The Golden Girls," a sitcom about four older women living together in Miami that featured an age demographic rarely highlighted on American television. White also was nominated for an Emmy six other times for her portrayal of the widowed Rose Nylund, a sweet, naive and ditzy Midwesterner, on the show, which ran from 1985 to 1992 and was one of the top-rated series of its time. After a less successful sequel to "The Golden Girls" came a series of small movie parts, talk-show appearances and one-off television roles, including one that won her an Emmy for a guest appearance on "The John Larroquette Show." By 2009 she was becoming ubiquitous with more frequent television appearances and a role in the Sandra Bullock film "The Proposal." She starred in a popular Snickers candy commercial that aired during the Super Bowl, taking a brutal hit in a mud puddle in a football game. A young fan started a Facebook campaign to have White host "Saturday Night Live" and she ended up appearing in every sketch on the show and winning still another Emmy for it. The Associated Press voted her entertainer of the year in 2010 and a 2011 Reuters/Ipsos poll found that White, then 89, was the most popular and trusted celebrity in America with an 86% favorability rating. White"s witty and brassy demeanor came in handy as host of "Betty White"s Off Their Rockers," a hidden-camera show in which elderly actors pulled pranks on younger people. "Who would ever dream that I would not only be this healthy, but still be invited to work?" White said in a 2015 interview with Oprah Winfrey. White, who had no children, worked for animal causes. She once turned down a role in the movie "As Good as It Gets" because of a scene in which a dog was thrown in a garbage chute. She looked forward to her milestone birthday, writing on Twitter just three days before her death, "My 100th birthday ... I cannot believe it is coming up."